<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2017-01-03</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001012477</issuerCik>
        <issuerName>AVADEL PHARMACEUTICALS PLC</issuerName>
        <issuerTradingSymbol>AVDL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001318487</rptOwnerCik>
            <rptOwnerName>VAN ASSCHE BENOIT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BLOCK 10-1, BLANCHARDSTOWN</rptOwnerStreet1>
            <rptOwnerStreet2>CORPORATE PARK, BALLYCOOLIN</rptOwnerStreet2>
            <rptOwnerCity>DUBLIN 15</rptOwnerCity>
            <rptOwnerState>L2</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>IRELAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>/s/ Phillandas T. Thompson as attorney in fact for Benoit Van Assche</signatureName>
        <signatureDate>2017-01-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
